Over the years, the competition between Novak Djokovic and Roger Federer has evolved from being merely incredible to genuinely mind-boggling, as one glance at the statistics and memorable moments will show. But perhaps the tale of their rivalry is best told by some of its overlooked details.
The men, seeded No. 1 (Djokovic) and 3 (Federer) at the Australian Open, will meet for the 45th time in the semifinals at Melbourne Park on Thursday (live on ESPN/WatchESPN, 3:30 a.m. ET) and are tied at 22 wins apiece.
It's a remarkable record distinguished by almost symphonic balance, a comprehensive symmetry that makes this Federer-Djokovic rivalry the richest, most resonant and just plain best of all time.
With the exception of round-robin clashes dictated by the ATP World Tour Finals format, these men have not met before the semifinal stage at any tournament since the quarterfinals of the Dubai tournament in 2007.
Only Federer has won more than three consecutive matches, and that was at the very start of the rivalry when Federer was an accomplished 24-year-old and Djokovic a callow teenager at 18.
Surface hardly matters in this rivalry, as each man has won and lost against the other at every Grand Slam, with Djokovic holding an 8-6 edge in majors matches.
While Djokovic has a comparably close rivalry with Rafael Nadal and the two have played three more matches, the results haven't been nearly as balanced. The head-to-head record is similar (24-23), but Nadal is 14-6 against Djokovic on clay while Federer is a surprising 4-4. Djokovic is also currently on a five-match winning streak against Nadal, with no end in sight.
And if you appreciate irony, you might consider the way all of this has played out over the past few years as a great example of poetic justice meted out on Federer's behalf.
Consider: Federer is the all-time, three-surface Grand Slam singles champion, yet he had the misfortune to be good enough to reach all those clay court semifinals and finals against Nadal at his "King of Clay" peak -- which left Federer at the wrong end of a 23-11 head-to-head record, with Nadal ahead 13-2 on clay. That rivalry has since been put in the shade, and Nadal's claim to being the greatest of all time has weakened.
Of course, Federer's rivalry with Djokovic is also destined to lose its luster one day, and for the same reason it has attained its special glow: Federer's longevity. He's 34, yet he's managed stand fast as the main threat to Djokovic's dominion. His ability to block Djokovic's path is a testament to the defiant perseverance of his mind and spirit, as well as his body.
Thursday's semifinal in Melbourne could be a pivotal meeting for Federer, but not because the lead in the rivalry is up for grabs. Federer's 34-year-old counterpart Serena Williams is still the dominant player on the women's tour, but the feeling among pundits is that Federer no longer has Williams' firm grip on that role on the men's side, that he may no longer be able to beat Djokovic in five-set matches, presumably because that format requires more mental and physical stamina.
Federer doesn't particularly like that theory, but Djokovic is open to it. It's understandable, because Djokovic hasn't lost against Federer at a Grand Slam event since the 2012 Wimbledon semifinals. Federer went on to win it all that year, but he hasn't won a major since.
On Tuesday after he had secured his place in the semis, Djokovic told the press that the five-set format might give him an advantage. "But ... I don't think there is too much difference playing Roger in a Grand Slam. Any round feels like the finals because we are big rivals, we played so many times against each other. There's a lot of tension. There's a lot at stake. I'm expecting a great fight in two days."
Djokovic is likely to get one, because Federer is coming into this tussle with something like a secret weapon. This tool enables him to do something that most of his peers -- including Nadal -- have lost the ability to do when facing Djokovic: He enjoys himself. He says he's having fun. Can you imagine?
"I feel like I'm competitive at the top," Federer told reporters after he booked his 45th date with Djokovic. "It's nice now that, in the last three Slams, that I've been as consistent as I have been. I'm playing good tennis, fun tennis for me, anyway. I really enjoy being able to come to the net more, like back in the day. So I'm very pleased. It would mean a lot to me [to win another major], no doubt about it."
Time, though, is clearly on Djokovic's side. So is the arc of his career, even as Federer hangs on.
"I did go through my moments, periods of my career, where I was doubting myself, not knowing really if I can manage to ... break the dominance of these two guys," Djokovic said, referring to Federer and Nadal. "Of course, I've been through those moments, but those moments made me tougher."
The dominance of "those two guys" has been broken, but for the moment, at least one of those men is anything but vanquished.